There are a range of clinical syndromes that require some form of ventilation therapy. These syndromes may include hypoxemia, various forms of respiratory insufficiency and airway disorders. There are also non-respiratory and non-airway diseases that require ventilation therapy, such as congestive heart failure and neuromuscular disease, respectively.
Different and separate from ventilation therapy, is oxygen therapy, used for less severe forms of respiratory insufficiency. The standard of care for oxygen therapy or long term oxygen therapy (LTOT) includes administering supplemental oxygen to the patient with a small bore nasal cannula, using a metering device known as an oxygen conserver that releases the oxygen in boluses during a patient's inspiratory phase. This therapy is not considered ventilation therapy or respiratory support, because it does not mechanically help in the work of breathing.
Some entrainment mask systems have been developed and used for the purpose of delivering proper mixtures of air and therapeutic gas. For example, oxygen reservoir systems exist that include a mask with ports to entrain room air. Or, high flow oxygen delivery systems exist that include an air-entrainment mask containing a jet orifice and air entrainment ports, are designed to fit over the patient's nose and mouth, and connect to oxygen supply tubing. Oxygen under pressure is forced through a small jet orifice entering the mask. The velocity increases causing a shearing effect distal to the jet orifice, which causes room air to be entrained into the mask. These oxygen therapy entrainment systems do not support the work of breathing of the patient, rather they are used to deliver proper mixtures of air and oxygen.
Recently, a variant of oxygen therapy has been employed, known as high flow oxygen therapy (HFOT). In this case, the oxygen flow rate is increased beyond standard LTOT, for example, above 10 LPM. Because of the high flow rate, the oxygen must be humidified to prevent drying out the patient's airway. It has been reported that HFOT can reduce the patient's pleural pressure during spontaneous breathing. These systems are inefficient in that they are not precise in delivery of the therapy, and they consume a significant quantity of oxygen, which is often a drawback because the system cannot be mobile.
Respiratory support and ventilation therapies provide mechanical ventilation (MV) to the patient, and mechanically contribute to the work of breathing. MV therapies interface with the patient by intubating the patient with a cuffed or uncuffed tracheal tube, or a sealing face mask, sealing nasal mask or sealing nasal cannula. While helpful in supporting the work of breathing, the patient interfaces used for MV are obtrusive and/or invasive to the user, and MV does not facilitate mobility or activities of daily living and is therefore a drawback to many potential users.
Non-invasive ventilation (NIV) is used to ventilate a patient without requiring intubation. This is a significant advantage in that the patient does not require sedation for the therapy. However, the patient cannot use their upper airway because the interface makes an external seal against the nose and/or mouth, and the system is not mobile, the combination of which does not enable activities of daily living.
Minimally invasive ventilation (MIV) has been described to ventilate a patient with a catheter based delivery system that does not close the airway, and the patient can breathe ambient air freely and naturally through their normal passage ways. MIV differs from NIV because in NIV the patient interface does not enter the person's body, or minimally enters the body, and no unnatural channels are required to gain access to the airway, whereas MIV requires a slightly penetrating catheter or interface into an airway, and/or requires an unnatural channel to be created for airway access. MIV therapies have some promise; however, the patient needs to tolerate a transcutaneous catheter, for example a percutaneous transtracheal catheter, which can be beneficial for those whom are already trached or for those whom wish to conceal the interface underneath clothing.
For treating obstructive sleep apnea (OSA), the gold standard ventilation therapy is continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP), which is a variant to NIV in that the patient partially exhales through exhaust ports in the mask and exhales the balance back into the large deadspace mask and large gas delivery tubing. The continuous positive pressure being applied from the ventilator opens the upper airway, using a patient interface mask that seals over the nose and or mouth, or seals inside the nose. While highly effective in treating OSA, this therapy has poor patient compliance because the patient interface is obtrusive to the patient, and because the patient unnaturally breathes through a mask and gas delivery circuit. A lesser obtrusive BiPAP and CPAP patient interface has been described by Wondka (U.S. Pat. No. 7,406,966), which is used for both NIV and OSA, in which the interface is low profile and allows for an adjustable fitment and alignment with the user's face and nose. The interface solves many of the preexisting problems associated with NIV masks and OSA masks, namely leaks, comfort, tolerance, sleep position, pressure drop and noise, and compatibility with a variety of anatomical shapes.
In summary, existing therapies and prior art have the following disadvantages: they do not offer respiratory support or airway support in a manner that (1) is non-invasive, and un-obtrusive such that it allows for mobility and activities of daily living, (2) allows the sensation of breathing from the ambient surroundings normally, and (3) is provided in an easily portable system or a system that can be easily borne or worn by the patient.